Legendary dinosaur king didn’t survive on fast food

According to the latest installment in the ongoing saga over the
king of dinosaurs' dietary habits,
Tyrannosaurus rex was not simply an oversize scavenger. By the time
T. rex was lucky enough to find a carcass, smaller animals
would have stripped it to the bone first, claims a new study of the
giant dino's fierce competition for rotting flesh.

The January 26 study in Proceedings of the Royal Society
B doesn't explore what T. rex hunted, but it counters earlier
research that suggested the creature could survive only on carrion
when it roamed North America some 65 million years ago.

"This has been a discussion for as long as we've known about [T.
rex's] existence," said study co-author and ecologist Chris Carbone
of the Institute of Zoology in London. "Some people say it's a
settled issue, that it both scavenged and hunted, but evidence is
scarce and we see both extremes in behavior in large carnivores
today."

Adult tyrannosaurs were about 40 feet long, 15 feet high and
weighed between five and seven tons, making them one of the largest
land-based carnivores ever. However, they shared features common to
both full-time scavengers and predators, causing debate about how
they subsisted.

Powerful jaws, impact-resistant teeth and huge size are all
associated with predatory behavior. An enhanced sense of smell,
small eyes and puny forelimbs are associated with scavenging.
Previous studies tallied up T. rex's energy costs, determining that
a Serengeti-like environment could
support the seven-ton toothy beasts on carcasses alone.

But that research took too narrow a view of dinosaur life,
counting how many calories T. rex needed but not the competition it
faced in getting them, said Carbone.

"In that study they essentially fed T. rex carrion hamburgers at
a regular interval, which resolved the question of energy intake," he said. "The approach was
good, but it was in isolation. We found this argument breaks down
quickly in an ecological context."

To see if T. rex could survive on a carrion diet, Carbone's team
developed a computer model that merged dinosaur abundance, based on
fossils found in the same formations as T. rex, with modern
Serengeti scavenging data. Because predator-to-prey ratios in the
fossil record are similar to ratio in Africa's scavenger-filled
savannas, Carbone said the Serengeti was a good model to bring all
of the dinosaur abundance and territory data into perspective.

They concluded that T. rex would have faced such fierce
competition from smaller scavenging dinos, that carrion alone
wouldn't suffice as a primary food source.